Methods, systems, and assemblies for cooling an electronic component

ABSTRACT

Methods, systems, and assemblies for cooling an electronic component are disclosed. A heat sink assembly includes first and second substrates. The first substrate is in thermal contact with the electronic component. A primary channel is formed in the second surface of the first substrate. The primary channel is configured to direct cooling fluid for cooling the electronic component. An array of primary cooling fluid fins is positioned within the primary channel. The array of primary cooling fluid fins includes upstream solid fins and downstream open fins each having an upstream opening and downstream sidewalls. The secondary channel is formed within the second surface of the second substrate and is configured to direct partially heated cooling fluid away from the electronic component. An array of secondary cooling fluid fins is positioned within the secondary channel downstream. An enclosing layer seals the secondary channel.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a divisional application and claims priority benefitto, co-pending U.S. patent application Ser. No. 15/869,173, filed onJan. 12, 2018, which claims the benefit of U.S. Application Nos.62/445,296, filed Jan. 12, 2017, and 62/613,343, filed Jan. 3, 2018. Allof the above-mentioned applications are incorporated by reference as ifdisclosed herein in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant no.HR0011-13-2-0013 awarded by the Defense Advanced Research ProjectsAgency. The government has certain rights in the invention.

BACKGROUND

Power densities in electrical components have reached unprecedentedlevels as processing power increases in ever decreasing package sizes.In some cases, heat fluxes from component surfaces are so large that theheat loads cannot be mitigated through conventional cooling technology.These heat fluxes can extend well beyond 1 kW/cm². Overheating inelectrical components, such as integrated circuits, can result in excesssignal noise, reduced component operational lifetimes, and mechanicalfailures.

Thus advanced embedded or integrated heat sinks are being developed forthe newest generation of computing, laser, radar, and diode systems,amongst others, to handle heat fluxes in excess of 1 kW/cm². In suchembedded or integrated cooling systems, a cooling fluid flows around,between, and/or through positions of the electrical component to providecooling at the heat source. Strong initiatives have been put in placerecently by both industry and government bodies to develop theseadvanced heat sinks, the Defense Advanced Research Projects Agency(DARPA) Intrachip/Interchip Enhanced Cooling Fundamentals (ICECoolFundamentals) program being an example.

SUMMARY

Some embodiments of the disclosed subject matter include a heat sinkassembly for cooling an electronic component including the following: afirst substrate including first and second surfaces, the first surfacebeing in thermal contact with the electronic component; a primarychannel formed in the second surface of the first substrate, the primarychannel being configured to direct cooling fluid for cooling theelectronic component; an array of primary cooling fluid fins positionedwithin the primary channel, the array of primary cooling fluid finsincluding upstream solid fins and downstream open fins each including anupstream opening and downstream sidewalls; a second substrate includingfirst and second surfaces with the first surface of the second substratepositioned in thermal contact with the second surface of the firstsubstrate, the second substrate including cooling fluid conduits havingupstream and downstream ends and each being formed through the secondsubstrate from the upstream end at the first surface to the downstreamend at the second surface; a secondary channel formed within the secondsurface of the second substrate, the secondary channel being configuredto direct partially heated cooling fluid away from the electroniccomponent; an array of secondary cooling fluid fins positioned withinthe secondary channel downstream, each being positioned downstream ofone of the fluid conduits; an enclosing layer for sealing the secondarychannel; a cooling fluid inlet formed in the primary channel; and acooling fluid outlet formed in at least one of the enclosing layer andthe secondary channel.

Some embodiments of the disclosed subject matter include a system forcooling an electronic component that includes the following: a coolingfluid source; a heat sink assembly as described above positioned inthermal contact with the electronic component, the heat sink assemblyincluding a cooling fluid inlet and a cooling fluid outlet; conduits forjoining the cooling fluid inlet and outlet in fluid communication withthe cooling fluid source; and a pump positioned between the coolingfluid source and the cooling fluid inlet of the heat sink assembly, thepump being configured to draw a cooling fluid from the cooling fluidsource and pump it into the heat sink assembly via the cooling fluidinlet and through the heat sink assembly to the cooling fluid outlet.

Some embodiments of the disclosed subject matter include a method ofcooling an electronic component that includes the following: positioninga heat sink assembly including a bi-directional cooling fluid flow pathin thermal communication with the electronic component; providing asupply of a cooling fluid having a first temperature; directing thecooling fluid having a first temperature through the heat sink assemblyin a first direction that is substantially parallel to a plane definedby a surface of the electronic component in thermal communication withthe heat sink assembly so that the cooling fluid having a firsttemperature is in thermal communication with a portion of the heat sinkassembly in thermal communication with the electronic component;directing the cooling fluid having a second temperature that is greaterthan the first temperature in a second direction that is substantiallyperpendicular to the plane defined by the surface of the electroniccomponent in thermal communication with the heat sink assembly;directing the cooling fluid having a second temperature in a thirddirection that is substantially parallel to the first direction; andcontinuously repeating prior steps while the electronic component isenergized.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show embodiments of the disclosed subject matter for thepurpose of illustrating the invention. However, it should be understoodthat the present application is not limited to the precise arrangementsand instrumentalities shown in the drawings, wherein:

FIG. 1 is a schematic diagram of systems and methods according to someembodiments of the disclosed subject matter;

FIG. 2 is an enlarged partial isometric view of a fluid cooling assemblypositioned on an electronic component according to some embodiments ofthe disclosed subject matter;

FIG. 3 is enlarged exploded isometric view of the fluid cooling assemblyin FIG. 2 according to some embodiments of the disclosed subject matter;

FIG. 4 is a top plan view of an array of primary fluid cooling finsaccording to some embodiments of the disclosed subject matter;

FIG. 5 is a top plan view of an array of secondary fluid cooling finsaccording to some embodiments of the disclosed subject matter;

FIG. 6 is an enlarged partial isometric view of a fluid cooling assemblypositioned on an electronic component according to some embodiments ofthe disclosed subject matter;

FIG. 7 is an enlarged top plan view of a primary fluid cooling finaccording to some embodiments of the disclosed subject matter;

FIG. 8 is an enlarged top plan view of a secondary fluid cooling finaccording to some embodiments of the disclosed subject matter; and

FIG. 9 is a chart of methods of cooling an electronic componentaccording to some embodiments of the disclosed subject matter.

DETAILED DESCRIPTION

Referring now to FIG. 1, some embodiments of the disclosed subjectmatter include a system 100 for cooling an electronic component 102 thatcirculates a cooling fluid 104 through a heat sink assembly 106 that isin thermal contact with the electronic component. In some embodiments,system 100 is stamped, machined, molded, or 3D-printed from one or morematerials as discussed in greater detail below.

Cooling fluid 104 is supplied from a cooling fluid source 108 to heatsink assembly 106 via conduits 110. In some embodiments, cooling fluid104 is any fluid or gas suitable for extracting heat from heat sinkassembly 106. In some embodiments, cooling fluid 104 is ahydrofluoroether. Some embodiments include a second cooling fluid source112 in fluid communication with cooling fluid source 108 and/or heatsink assembly 106.

Heat sink assembly 106, which is described in further detail below,includes first and second substrates 114 and 116, respectively, whichare joined with one another via known bonding methods, including but notlimited to, direct fusion, adhesive bonding, welding, etc. Heat sinkassembly 106 includes at least one cooling fluid inlet 118 and at leastone cooling fluid outlet 120, both of which are joined with coolingfluid source 108 and/or cooling fluid source 112 via conduits 110.

System 100 includes a pump 122 positioned between cooling fluid source108 and cooling fluid inlet 118 of heat sink assembly 106. Pump 122 ispositioned and configured, e.g., sized, etc., to draw cooling fluid 104from cooling fluid source 108 via one 124 of conduits 110 and pump itinto the heat sink assembly via cooling fluid inlet 118 and through heatsink assembly 106 to the cooling fluid outlet 120. As it is at leastpartially heated, i.e., it has a temperature that is higher than when itfirst entered heat sink assembly 106, cooling fluid 104 is transformedso as to be identified as cooling fluid 104′ when adjacent cooling fluidoutlet 120. In some embodiments, a second pump 126 is positioned andconfigured, e.g., sized, etc., to draw cooling fluid 104′ from heat sinkassembly 106 via cooling fluid outlet 120 via one 128 of conduits 110and to either a cooling tank (not shown), to second cooling fluid source112, or to cooling fluid source 108.

In some embodiments, system 100 includes a control module 130 that hastemperature sensors 132 and 134 for determining temperatures of coolingfluid 104 and 104′ in cooling fluid supply 108 and conduits 110 and atemperature of a surface of electronic component 102 adjacent heat sinkassembly 106. Control module 130 includes a computer device 136 and oneor more software programs 138 for processing temperature data, e.g.,from temperature sensors 132 and/or 134. In some embodiments, thetemperature data is used to determine whether pumps 122 and 126 areactivated and to what extent, e.g., at what flow rate. In someembodiments, control module 130 is connected with all of the componentsin system 100 and controls the components either manually orautomatically depending on sensor data. In some embodiments, othersensors for measuring other characteristics of fluid flow, e.g.,pressure, velocity, etc., are included. Sensors included with controlmodule 130 are wired or wireless depending on the particularapplication.

Referring now to FIGS. 2-8, some embodiments include a heat sinkassembly 206 (analogous to heat sink assembly 106 above), for coolingelectronic component 102. Heat sink assembly 206 includes first andsecond substrates 208 and 210, respectively, which form an at leastbi-directional and bi-axial pathway 212 through which cooling fluids 104and 104′ flow. In some embodiments, heat sink assembly 206 includes twoor more first substrates 208.

First substrate 208 includes first and second surfaces 214 and 216,respectively. First surface 214 is in thermal contact with electroniccomponent 102. A primary channel 218 is formed in second surface 216 offirst substrate 208. Primary channel 218 is configured to direct coolingfluid 104 and 104′ for cooling electronic component 102 through heatsink 206. As best shown in FIG. 4, an array 220 of primary cooling fluidfins 222 is positioned within primary channel 218. As best shown inFIGS. 4 and 7, array 220 of primary cooling fluid fins 222 includesupstream solid fins 224 and downstream open fins 226. As used herein,upstream and downstream are relative to pathway 212 through whichcooling fluids 104 and 104′ flow. Each of open fins 226 includes anupstream opening 228 and downstream sidewalls 230. As mentioned above, acooling fluid inlet 232 is formed in primary channel 218. Primarychannel 218 is substantially parallel to a plane 234, which is definedby a surface 236 of electronic component 102 that is in thermalcommunication with heat sink assembly 206. In some, embodiments, primarychannel 218 includes a cooling fluid outlet 238 downstream of array 220of primary cooling fluid fins 222.

Second substrate 210 includes first and second surfaces 240 and 242,respectively, with the first surface positioned in thermal contact withsecond surface 216 of first substrate 208. In some embodiments, firstand second substrates 208 and 210 are joined with one another via directfusion. Depending on the application, in some embodiments first andsecond substrates 208 and 210 may be bonded together by other means,e.g., welded, glued, etc., known to those skilled in the art. First andsecond substrates 208 and 210 are typically, but not always, formedsubstantially from silicon-based materials. In some embodiments, firstand second substrates 208 and 210 are formed substantially of siliconcarbide. In some embodiments, first and second substrates 208 and 210are formed substantially of silicon. In some embodiments, first andsecond substrates 208 and 210 are formed substantially of metal. In someembodiments, first and second substrates 208 and 210 are formedsubstantially of copper. As best shown in FIG. 6, second substrate 210includes cooling fluid conduits 244 that are substantially perpendicularto plane 234 defined by surface 236 of electronic component 102. Each ofcooling fluid conduits 244 have upstream and downstream ends 246 and248, respectively, that are each formed through the second substratefrom the upstream end at first surface 240 to the downstream end atsecond surface 242. In some embodiments, primary channel 218 isconfigured so that substantially all of cooling fluid 104 and 104′ thatenters the primary channel exits the primary channel via cooling fluidconduits 244. Referring again to FIG. 3, a secondary channel 250 isformed within second surface 242 of second substrate 210. Secondarychannel 250 is configured to direct partially heated cooling fluid 104′away from electronic component 102. As best shown in FIGS. 3 and 5, anarray 252 of secondary cooling fluid fins 254 is positioned withinsecondary channel 250. Array 252 is positioned downstream of downstreamend 248 of one of fluid conduits 244. As best shown in FIG. 8, each ofsecondary cooling fluid fins 254 includes a shroud portion 256 definedaround a portion 258 of downstream end 248 of one of cooling fluidconduits 244. Shroud portion 256 is configured to prevent stagnationzones of partially heated cooling fluid 104′ from forming adjacentdownstream ends 248 of cooling fluid conduits 244. Secondary channel 250is substantially parallel to plane 234 defined by surface 236 ofelectronic component 102.

Referring again to FIG. 3, an enclosing layer 259 is joined with secondsurface 242 of second substrate 210 and seals secondary channel 250.Although not necessary, in some embodiments, enclosing layer 259 isformed from a substantially transparent material such as glass, orsimilar. A cooling fluid outlet 260 is formed in one of enclosing layer259 and secondary channel 250 for allowing partially heated coolingfluid 104′ to exit heat sink assembly 206 via cooling outlet 238 infirst substrate 208.

Referring now to FIG. 9, some embodiments of the disclosed subjectmatter include a method 300 of cooling an electronic component. At 302,a heat sink assembly including a bi-directional cooling fluid flow pathis positioned in thermal communication with the electronic component. At304, a supply of a cooling fluid having a first temperature is provided.At 306, the cooling fluid having a first temperature is directed throughthe heat sink assembly in a first direction that is substantiallyparallel to a plane defined by a surface of the electronic component inthermal communication with the heat sink assembly so that the coolingfluid having a first temperature is in thermal communication with aportion of the heat sink assembly in thermal communication with theelectronic component. At 308, the cooling fluid having a secondtemperature that is greater than the first temperature is directed in asecond direction that is substantially perpendicular to the planedefined by the surface of the electronic component in thermalcommunication with the heat sink assembly. At 310, the cooling fluidhaving a second temperature is directed in a third direction that issubstantially parallel to the first direction. In some embodiments, at312, the cooling fluid having a second temperature is mixed with coolingfluid having a lower temperature until the cooling fluid having a secondtemperature is at the first temperature thereby producing a recycledcooling fluid that can be used at step 304. In some embodiments, thecooling fluid having a lower temperature is the cooling fluid having afirst temperature from the supply. In some embodiments, the coolingfluid having a lower temperature is introduced from a second supply ofcooling fluid. At 314, prior steps are continuously repeating while theelectronic component is energized. In some embodiments, method 300includes providing one or more pumps for directing both the coolingfluid having a first temperature and the cooling fluid having a secondtemperature through the heat sink assembly.

Methods and systems according to the disclosed subject matter provideadvantages and benefits over known methods and systems by being capableof dissipating ultra-high heat fluxes, e.g., from electronic components.The cooling fluid is directed to a primary substrate which communicatesheat from a heat source to the cooling fluid. Primary cooling fins ofthe primary substrate are positioned and shaped to direct the heatedcooling fluid away from the first substrate through a secondarysubstrate via a cooling fluid conduit, which advantageously conductsheat further away from the heat source, and improves the efficiency ofthe heat sink. The secondary substrate itself provides an additionalheat transfer chamber, and acts to stabilize flow of cooling fluidthrough the system. The secondary substrate also allows inclusion ofsecondary cooling fins which include a shroud portion that mitigatesstagnation zones as the heated cooling fluid flows around them. Thesefeatures are scalable and 3D printable for simple design and fabricationfor specific applications. Further, the components of the presentdisclosure are easily integrated and/or embedded into relativelyconventional systems, e.g., transistor networks, integrated circuitnetworks, etc.

Although the disclosed subject matter has been described and illustratedwith respect to embodiments thereof, it should be understood by thoseskilled in the art that features of the disclosed embodiments can becombined, rearranged, etc., to produce additional embodiments within thescope of the invention, and that various other changes, omissions, andadditions may be made therein and thereto, without parting from thespirit and scope of the present invention.

What is claimed is:
 1. A system for cooling an electronic component,said system comprising: a cooling fluid source; a heat sink assemblypositioned in thermal contact with said electronic component, the heatsink assembly comprising: a first substrate including first and secondsurfaces, said first surface being in thermal contact with saidelectronic component; a primary channel formed in said second surface ofsaid first substrate, said primary channel being configured to directcooling fluid for cooling said electronic component; an array of primarycooling fluid fins positioned within said primary channel, said array ofprimary cooling fluid fins including upstream solid fins and downstreamopen fins, wherein each downstream open fin includes an upstream openingand downstream sidewalls; a second substrate including first and secondsurfaces with said first surface of said second substrate positioned inthermal contact with said second surface of said first substrate, saidsecond substrate including cooling fluid conduits having upstream anddownstream ends and each being formed through said second substrate fromsaid upstream end at said first surface of said second substrate to saiddownstream end at said second surface of second substrate; a secondarychannel formed within said second surface of said second substrate, saidsecondary channel being configured to direct partially heated coolingfluid away from said electronic component; an array of secondary coolingfluid fins positioned within said secondary channel, each beingpositioned downstream of said downstream end of one of said fluidconduits; an enclosing layer for sealing said secondary channel; acooling fluid inlet formed in said primary channel; and a cooling fluidoutlet formed in at least one of said enclosing layer and said secondarychannel; conduits for joining said cooling fluid inlet and outlet influid communication with said cooling fluid source; and a pumppositioned between said cooling fluid source and said cooling fluidinlet of said heat sink assembly, said pump being configured to drawsaid cooling fluid from said cooling fluid source and pump it into saidheat sink assembly via said cooling fluid inlet and through said heatsink assembly to said cooling fluid outlet.
 2. The system according toclaim 1, further comprising a control module including temperaturesensors for determining temperatures of said cooling fluid in saidcooling fluid source and said conduits and a temperature of a surface ofsaid electronic component adjacent said heat sink assembly.
 3. Thesystem according to claim 1, further comprising a second cooling fluidsource in fluid communication with said cooling fluid source.
 4. Thesystem according to claim 1, wherein said heat sink assembly includessaid first and second substrates being joined with one another viadirect fusion.
 5. The system according to claim 1, wherein said array ofsecondary cooling fluid fins each include a shroud portion definedaround a portion of said downstream end of one of said cooling fluidconduits, said shroud portion being configured to prevent a stagnationzone of partially heated cooling fluid from forming adjacent saiddownstream end of said one of said cooling fluid conduits.
 6. The systemaccording to claim 1, further comprising a second pump for pumping saidcooling fluid from said cooling fluid source, through said heat sinkassembly via said cooling fluid inlet and outlet, and back to saidcooling fluid source.
 7. The system according to claim 1, wherein saidcooling fluid is a hydrofluoroether.
 8. A method of cooling anelectronic component, said method comprising: positioning a heat sinkassembly including a bi-directional cooling fluid flow path in thermalcommunication with said electronic component, the heat sink assemblyfurther including an array of primary cooling fluid fins positionedwithin a first flow path, said array of primary cooling fluid finsincluding upstream solid fins and downstream open fins, wherein eachdownstream open fin includes an upstream opening and downstreamsidewalls; providing a supply of a cooling fluid having a firsttemperature; directing said cooling fluid having a first temperaturethrough said heat sink assembly in a first direction that issubstantially parallel to a plane defined by a surface of saidelectronic component in thermal communication with said heat sinkassembly so that said cooling fluid having a first temperature is inthermal communication with a portion of said heat sink assembly inthermal communication with said electronic component; directing saidcooling fluid having a second temperature that is greater than saidfirst temperature in a second direction that is substantiallyperpendicular to said plane defined by said surface of said electroniccomponent in thermal communication with said heat sink assembly;directing said cooling fluid having a second temperature in a thirddirection that is substantially parallel to said first direction; andcontinuously repeating prior steps while said electronic component isenergized.
 9. The method according to claim 8, further comprising:producing recycled cooling fluid by mixing said cooling fluid having asecond temperature with cooling fluid having a lower temperature untilsaid cooling fluid having a second temperature is at said firsttemperature.
 10. The method according to claim 9, wherein said coolingfluid having a lower temperature is said cooling fluid having a firsttemperature from said supply.
 11. The method according to claim 8,further comprising providing one or more pumps for directing both saidcooling fluid having a first temperature and said cooling fluid having asecond temperature through said heat sink assembly.